Recently, a cable including a transmission line formed of a metal wire has been often used for signal transmission between electronic apparatuses. For example, High-Definition Multimedia Interface (HDMI; registered trademark) is well known as an interface of transmitting a digital video signal in an Uncompressed format. The HDMI cable transmission line is formed of a copper wire of a twisted line structure. Attenuation of the signal cannot be avoided during the transmission. In a cable including the transmission line formed of a copper wire, an upper limit of the distance in which a 2K digital video signal can be transmitted without error is several meters.
The cable length of several meters is sufficient for 2K video signal transmission. However, a purpose of use of the high-definition video signal such as 4K/8K (hereinafter totally called 8K) is limited by the cable having a length of several meters. A cable having a length of ten or more meters is required to be used for an 8K large television receiver.
An active optical cable (AOC) including a transmission line formed of an optical fiber is well known as a cable capable of transmitting a large amount of signals. To use the optical cable as the transmission line, a laser which converts an electric signal into an optical signal is required on the transmitting side, a photodiode which converts an optical signal transmitted through the optical fiber into an electric signal is required on the receiving side, and a power to drive the elements is required. This power is larger than a power for transmission of a general HDMI cable. Therefore, to implement the HDMI cable using the optical fiber, a power to drive the laser and the photodiode is required. To transmit the signal by the HDMI cable composed of the optical fiber, the electronic apparatus needs to be replaced with an apparatus comprising an ability to supply the power.